capture_requests {httptest2}

Record API responses as mock files

Description

capture_requests() is a context that collects the responses from requests you make and stores them as mock files. This enables you to perform a series of requests against a live server once and then build your test suite using those mocks, running your tests in with_mock_api().

Usage

capture_requests(expr, simplify = TRUE)

start_capturing(simplify = TRUE)

stop_capturing()

Arguments

expr

Code to run inside the context

simplify

logical: if TRUE (default), plain-text responses with status 200 will be written as just the text of the response body. In all other cases, and when simplify is FALSE, the httr2_response object will be written out to a .R file using base::dput().

Details

start_capturing() and stop_capturing() allow you to turn on/off request recording for more convenient use in an interactive session.

Recorded responses are written out as plain-text files. By storing fixtures as plain-text files, you can more easily confirm that your mocks look correct, and you can more easily maintain them without having to re-record them. If the API changes subtly, such as when adding an additional attribute to an object, you can just touch up the mocks.

If the response has status ⁠200 OK⁠ and the Content-Type maps to a supported file extension—currently .json, .html, .xml, .txt, .csv, and .tsv—just the response body will be written out, using the appropriate extension. ⁠204 No Content⁠ status responses will be stored as an empty file with extension .204. Otherwise, the response will be written as a .R file containing syntax that, when executed, recreates the httr2_response object.

Files are saved to the first directory in .mockPaths(), which if not otherwise specified is either "tests/testthat" if it exists (as it should if you are in the root directory of your package), else the current working directory. If you have trouble when recording responses, or are unsure where the files are being written, set options(httptest2.verbose = TRUE) to print a message for every file that is written containing the absolute path of the file.

Value

capture_requests() returns the result of expr. start_capturing() invisibly returns the destination directory. stop_capturing() returns nothing; it is called for its side effects.

See Also

build_mock_url() for how requests are translated to file paths. And see vignette("redacting", package = "httptest2") for details on how to prune sensitive content from responses when recording.

Examples

# Setup so that our examples clean up after themselves
tmp <- tempfile()
.mockPaths(tmp)
on.exit(unlink(tmp, recursive = TRUE))

library(httr2)
capture_requests({
  request("http://httpbin.org/get") %>% req_perform()
  request("http://httpbin.org/response-headers") %>%
    req_headers(`Content-Type` = "application/json") %>%
    req_perform()
})
# Or:
start_capturing()
request("http://httpbin.org/get") %>% req_perform()
request("http://httpbin.org/response-headers") %>%
  req_headers(`Content-Type` = "application/json") %>%
  req_perform()
stop_capturing()